A New Synthetic Route to Calcium Polyphosphates
This study describes the use of flux methods as a novel synthetic route to some known and new calcium polyphosphates, with a view to developing new biomaterials. Calcium acid pyrophosphate, CaH2P2O7, which is a known precursor in the preparation of many other calcium polyphosphates, has been synthesized as a pure crystalline phase in a single step synthesis at temperatures between 190-250 °C. Reaction temperatures between 250 and 400 °C led to the synthesis of γ-Ca(PO3)2, a previously uncharacterised polymorph of calcium metaphosphate. Lattice parameters of a = 10.3682(1) Å, b = 9.5001(1) Å, c = 9.5552(1) Å, with β angle of 93.45(4)° were obtained from powder X-ray diffraction data. A subsequent increase in reaction temperature to 550 °C was found to produce a calcium polyphosphate glass. A detailed study of thermal stability of CaH2P2O7 was also performed to determine phase stability and decomposition pathways.
Panjian Li, Kai Zhang and Clifford W. Colwell, Jr.
L. E. Jackson and A. J. Wright, "A New Synthetic Route to Calcium Polyphosphates", Key Engineering Materials, Vols. 284-286, pp. 71-74, 2005